首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
We repeatedly established a nontransformed steroidogenically active human ovarian cell culture derived from oophorectomy specimens. The cells maintained steroidogenic activity for 3-5 passages (6-8 weeks) and responded to stimulation by insulin and gonadotropin. With pregnenolone as substrate, LH stimulated progesterone production up to 124% and FSH up to 121%. Insulin alone stimulated progesterone production up to 135%, in the presence of LH up to 191%, and in the presence of FSH up to 170%. With dehydroisoandrosterone (DHA) as substrate, insulin alone stimulated testosterone production up to 117%, and in the presence of LH (but not FSH) up to 125%. With androstenedione as substrate, insulin alone stimulated estradiol production up to 133%, FSH alone up to 188%, and LH with insulin up to 217%. With progesterone as substrate and in the presence of LH (but not FSH), 17-alpha-hydroxylase activity was stimulated up to 131%. With DHA as substrate and in the presence of LH, 3-beta-hydroxysteroid dehydrogenase (3-beta-HSD) activity was stimulated up to 139%. With androstenedione as substrate, insulin alone stimulated aromatase activity up to 202%, LH up to 208%, and FSH up to 251%. Under the same conditions, in the presence of LH and insulin, aromatase activity was stimulated up to 342%, and in the presence of FSH and insulin, up to 318%. With testosterone as substrate, insulin alone stimulated aromatase activity up to 122%. With testosterone as substrate, in the presence of LH and insulin, aromatase activity was stimulated up to 136%, and in the presence of FSH and insulin, up to 156%. Immunocytochemistry studies directly confirmed presence of aromatase and 3-beta-HSD in these cultured cells. We conclude that a steroidogenically active nontransformed long-term human ovarian cell culture can be repeatedly established from oophorectomy specimens, providing uninterrupted supply of cultured human ovarian cells for a variety of studies of ovarian physiology.  相似文献   

2.
The objective of this pilot study was to determine the effect of 6 different abdominal exercises on the electrical activity of the upper rectus abdominis (URA) and lower rectus abdominis (LRA). Eight healthy, adult volunteers completed 6 random abdominal exercises: curl up, Sissel ball curl up, Ab Trainer curl up, leg lowering, Sissel ball roll out, and reverse curl up. Action potentials were recorded and analyzed from the URA and the LRA using surface electromyography (EMG) during a 2-second concentric contraction. The average normalized data were compared between the URA and the LRA in order to determine the behavior of the different muscle sites and between exercises in order to determine which exercises elicited the highest EMG activity. There were no significant differences (p > 0.05) between the EMG activity of the URA and LRA during any exercise. There were no significant interactions between subject and muscle site or between exercise and muscle site. Significant differences were found among the 6 exercises performed, and due to the interaction between subject and exercise performed. Both the URA and the LRA recorded significantly higher mean amplitudes during the Sissel ball curl up than during all other exercises. In addition, the curl up, Sissel ball curl up, and Ab Trainer curl up had significantly higher normalized EMG activity in both muscle sites than the reverse curl up, the leg lowering exercise, and the Sissel ball roll out. The curl up and the Ab Trainer curl up exercises were not significantly different in terms of their normalized EMG activities for both the URA and the LRA.  相似文献   

3.
The ability of growing mycoplasma cells and their isolated membranes to take up exogenous phospholipids was correlated with their ability to take up cholesterol. Horse serum or vesicles made of phosphatidylcholine and cholesterol served as lipid donors. Growing cells of five Mycoplasma species took up significant quantities of phosphatidylcholine and sphingomyelin as well as free and esterified cholesterol. In contrast, growing cells of three Acholeplasma species failed to take up any of the exogenous phospholipids, and only incorporated low amounts of free cholesterol and no esterified cholesterol. Hence, the ability of mycoplasmas to take up large quantities of cholesterol appears to be correlated with an ability to take up exogenous phospholipids. Isolated membranes of Mycoplasma capricolum and Acholeplasma laidlawii took up lower amounts of cholesterol than did membranes of growing cells and did not take up phospholipids. Inhibition of M. capricolum growth decreased the ability of the cells to take up exogenous phospholipids and cholesterol. The possibility that the contact between the lipid donors and the membrane involves specific receptors best exposed in actively growing cells is discussed.  相似文献   

4.
OBJECTIVE--To examine whether reactions of blood pressure to psychological stress predict future blood pressure. DESIGN--Blood pressure was recorded at a medical screening examination after which pressor reactions to a psychological stress task were determined. Follow up measurement of blood pressure was undertaken, on average, 4.9 years later. SETTING--20 civil service departments in London. SUBJECTS--1003 male civil servants aged between 35 and 55 years at entry to the study. MAIN OUTCOME MEASURE--Blood pressure at follow up screening. RESULTS--Reactions of systolic blood pressure to stress correlated positively with systolic blood pressure at follow up screening (r = 0.22, P < 0.01). The dominant correlate of follow up blood pressure was blood pressure at initial screening (r = 0.60; P < 0.01 between initial and follow up systolic blood pressure; r = 0.59, P < 0.01 between initial and follow up diastolic blood pressure). Stepwise multiple regression analysis indicated that reactions to the stressor provided minimal prediction of follow up blood pressure over and above that afforded by blood pressure at initial screening. In the case of follow up systolic blood pressure, systolic reactions to stress accounted for only 1% of follow up variance; systolic blood pressure at initial screening accounted for 34%. With regard to diastolic blood pressure at follow up, the independent contribution from diastolic reactions to stress was less than 1%. CONCLUSION--Pressor reactions to psychological stress provide minimal independent prediction of blood pressure at follow up. Measurement of reactivity is not a useful clinical index of the course of future blood pressure.  相似文献   

5.
A protamine kinase has been purified to apparent homogeneity from extracts of the cytosol of bovine kidney cortex. This protamine kinase exhibited an apparent Mr = 43,000 as estimated by gel permeation chromatography on Sephacryl S-200 and an apparent Mr = 45,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified protamine kinase exhibited about 5% activity with casein, 8% with histone H2B, and less than 0.1% with histone H1, histone H4, glycogen synthase a from rabbit skeletal muscle, ovalbumin, bovine serum albumin, and phosvitin. The activity of the highly purified protamine kinase was unaffected by cyclic AMP (up to 0.1 mM), cyclic GMP (up to 0.1 mM), the heat-stable protein inhibitor of cyclic AMP-dependent protein kinase (up to 100 micrograms/ml), heparin (up to 100 micrograms/ml), EGTA (up to 1 mM), Ca2+ (up to 1 mM), calmodulin (up to 0.5 microM) in the absence or presence of Ca2+ (0.05 mM), and phosphatidylserine (up to 40 micrograms/ml) and/or diolein (up to 1 microgram/ml) in the absence or presence of Ca2+ (up to 0.5 mM). Experiments in which extracts of kidney cytosol were incubated with [gamma-32P]ATP and MgCl2 revealed that the phosphorylation of numerous polypeptides was markedly increased in the presence of the purified protamine kinase. The results indicate that this protamine kinase of kidney cytosol is a novel protein kinase.  相似文献   

6.
广西植被植物区系研究   总被引:4,自引:1,他引:3  
苏宗明   《广西植物》1997,17(1):60-68
广西植被植物区系组成有217科,1025属,乔木层优势种430种。分层统计,乔木层278属,灌木层198属,草本层403属,层间植物145属。927属种子植物有14个分布区类型和19个变型,热带分布占73.0%,温带分布占23.8%。分层:乔木层热带分布占74.1%,温带分布占19.8%,草本层热带分布占68.6%,温带分布占29.8%;泛热带分布42.5%在草本层,22.5%在乔木层;热带亚洲分布37.5%在乔木层,20.7%在草本层;北温带分布48.4%在草本层,30.6%在乔木层;东亚和北美洲间断分布37.5%在乔木层,17.5%在草本层;东亚分布44.4%在草本层,25.0%在乔木层。以优势种统计,热带分布占34.8%,南亚热带分布占28.8%,中亚热带分布占36.3%。  相似文献   

7.
An experiment was conducted to study the effect of microbial phytase (Natuphos® 500) supplementation in chicks fed different levels of available phosphorus (AP) and citric acid (CA) on performance, mineral retention (Ca, P, Mg, and Zn), bone and plasma minerals (Ca, P, Mg, and Zn), plasma total protein (TP), and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) activities. Data were analyzed as a 2×4×2 factorial arrangement with two levels of AP (3.5 and 2.5 g/kg), four levels of phytase (0, 200, 400 and 600 U/kg), and two levels of citric acid (0 and 20 g/kg). The low-AP diets reduced performance. Phytase supplementation increased weight gain (up to 7% quadratically) and feed consumption (up to 5%). This response was statistically maximized by 200 U/kg phytase. Feed to gain ratio was not affected by phytase addition. Growth response to phytase was negatively affected by citric acid. Decreasing AP content in the diet increased Ca, P, and Mg retention, and reduced Zn retention. Phytase supplementation linearly increased Ca, P, and Zn retention by 9, 10 and 16%, respectively. Citric acid addition also increased Ca, P, and Zn retention by 3, 3 and 4%, respectively. Likewise, the decrease in AP content in the diet caused a reduction of tibia ash and tibia Zn, and an increase in tibia Ca and P contents. Phytase supplementation increased tibia ash (up to 4%), tibia Ca (up to 2%), P (up to 1%) and Zn (up to 4%) contents, tibia weight (up to 9%), and relative tibia (up to 19%) and liver (up to 13%) weights. Citric acid increased tibia ash (2%), and tibia Ca (2%) and P (2%) contents. Finally, by decreasing AP levels in the diet, plasma Ca and Zn concentrations as well as AST, ALP, and LDH activities were increased. However, plasma P and TP content were reduced. Phytase supplementation increased linearly plasma Ca (up to 4%), P (up to 12%), Mg (up to 10%), Zn (up to 22%) and TP (up to 7%) content, and serum AST (up to 22%), ALT (up to 40%), and LDH (up to 17%) activities, and reduced linearly serum ALP (up to 34%) activity. Citric acid addition increased plasma Ca, Mg, and Zn content by 10, 4, and 5%, respectively, and reduced ALP activity by 13%. In conclusion, these results indicated that the addition of phytase to maize and soyabean meal low-AP diets improved the performance and increased Ca, P, and Zn utilization in chicks. However, the inclusion of citric acid depressed the performance and caused an increase in mineral utilization. Growth response to phytase was negatively affected by citric acid.  相似文献   

8.
Despite their important role in regulating gene expression, posttranslational histone modifications remain technically challenging to analyze. For identification by bottom‐up MS, propionylation is required prior to and following trypsin digestion. Hereby, more hydrophobic peptides are generated enabling RP HPLC separation. When histone dynamics are studied in a quantitative manner, specificity, and efficiency of this chemical derivatization are crucial. Therefore we examined eight different protocols, including two different propionylation reagents. This revealed amidation (up to 70%) and methylation (up to 9%) of carboxyl groups as a side reaction. Moreover, incomplete (up to 85%) as well as a specific propionylation (up to 63%) can occur, depending on the protocol. These results highlight the possible pitfalls and implications for data analysis when doing bottom‐up MS on histones.  相似文献   

9.
Embryogenesis of Payer's patches (PP) of the ileum, has been studied in 183 human fetuses 8-40-week-old. Their anlages appear on the 8th-9th week as an accumulation of atypical villi. At first the PP are localized in the cranial part of the ileum, and then spread caudally. Their most active increase in amount takes place from the 15th up to 17th weeks of development. From the 8th up to the 40th weeks the PP amount increase from 10 up to 37. During the same time their length develops from 0.7 up to 8.3 mm, their width--from 0.3 up to 2.2. The first lymphoid nodules++ in the PP are detected on the 14th week, then their number rises from 200 up to 3,500. The superficial area of all the PP, turning into the lumen of the ileum widens from 1.4 up to 620 mm2. Their predominate form is ellipsoid. During the whole prenatal period in the lymphoid nodules++ no germinative centers are revealed. Lymphocytes in the PP are identified in 8-9-week-old fetuses. By the 29th week the whole amount of lymphocytes in them increase up to 9.6 x 10(6) cells. Lymphocytic suspension of the PP of 8-9-week-old fetuses contains 1.7% of T-lymphocytes (E = POK) and 0.1% of B-lymphocytes (EAC = POK). By the 29th week their amount increases up to 9% and 7%, respectively, but by birth it does not reach their amount in the PP of mature organisms.  相似文献   

10.
The composition of 48 samples of essential oil isolated from the wood of Cedrus atlantica growing in Corsica was investigated by GC (in combination with retention indices), GC/MS, and (13) C-NMR. Twenty-three compounds accounting for 73.9-96.0% of the oil composition were identified. The oils consisted mainly of monoterpene hydrocarbons and sesquiterpenes, in particular α-pinene (5; up to 79.4%), himachalol (4; up to 66.2%), β-pinene (up to 21.4%), β-himachalene (2; up to 19.3%), γ-himachalene (3; up to 11.0%), and α-himachalene (1; up to 10.9%). The 48 oil compositions were submitted to k-means partitioning and principal-component analysis, which allowed the distinction of two groups within the oil samples. The composition of Group I (44% of the samples) was dominated by 5, while the samples of Group II (56% of the samples) contained mainly 4.  相似文献   

11.
New polymeric Zn(salen) complex was employed in the enantioselective phenylacetylene addition to aldehydes and ketones to produce corresponding chiral secondary propargylic alcohols with yields (up to 96%) and enantioselectivity (up to 72%) and tertiary propargylic alcohols with yields (up to 79%) and enantioselectivity (up to 68%) at room temperature, with added advantage of four times reuse with retention of enantioselectivity.  相似文献   

12.
AIMS: Investigation of waste pulps and soda pulp bleaching with xylanase (X) and laccase mediator system (LMS) alone and in conjunction (one after the other) (XLMS). METHODS AND RESULTS: Soda and different grades of waste pulp fibres [used for making three-layered duplex sheets - top layer (TL), protective layer (PL) and bottom layer (BL)] when pretreated with either xylanase (40.0 IU g(-1)) or LMS (up to 200.0 U g(-1)) alone and in combination (one after the other) (XLMS) exhibited an increase in release of reducing sugars [up to 881.0% soda pulp; up to 736.6% (TL), up to 215.7% (PL) and up to 198.0% (BL) waste pulp], reduction in kappa number [up to 17.6% soda pulp; up to 14.0% (TL), up to 25.3% (PL) and up to 10.9% (BL), waste pulp], improvement in brightness [up to 20.4% soda pulp; up to 23.6% (TL), up to 8.6% (PL) and up to 5.0% (BL), waste pulp] when compared with the respective controls. The usage of XLMS along with 15% reduced level of hypochlorite at CEHHXLMS/EHHXLMS bleaching stage reduced kappa number [5.5% soda pulp; 11.4% (TL), 7.9% (PL), waste pulp] and improved brightness [1.0% soda pulp; 0.9% (TL), 1.4% (PL) waste pulp] when compared with the controls. Scanning electron microscopic studies revealed development of cracks, flakes, pores and peeling off the fibres in the enzyme-treated pulp samples. These modifications of the fibre surface during enzymatic bleaching in turn indicated the removal of lignin and derived compounds from the fibre cell wall. CONCLUSIONS: The work describes synergistic action of xylanase with LMS for bleaching of waste and nonwood pulps for eco-friendly production of paper and thus reveals a new unexploited arena for enzyme-based pulp bleaching. SIGNIFICANCE AND IMPACT OF THE STUDY: The drastic improvement in pulp properties obtained after xylanase and LMS treatment would improve the competitiveness of enzyme-based, environmentally benign processes over chemicals both economically and environmentally.  相似文献   

13.
圈养金钱豹行为谱   总被引:2,自引:1,他引:1  
2005年3月~2006年3月,采取所有事件取样法和目标取样法,对成都动物园圈养的17只金钱豹进行行为观察,在此基础卜制定了行为谱.研究表明:休息、观望、运动是圈养金钱豹的主要行为,占其所有行为的93.1%,休息占其所有行为的54.40%;观望占21.18%;运动占17.53%.  相似文献   

14.
We investigated the social function of tail up in order to verify its possible relationship with the hierarchical organization of a social group. Domestic cats live at higher densities than their ancestor which is a solitary species. Since the signals needed by solitary animals have different properties than those needed by group-living individuals, signalling pattern utilised by the domestic cat has inevitably changed. Kittens displayed the tail up when greeting their mother; this behaviour can also be observed in wild species. But, in domestic cat the tail up can be also observed when an adult individual meets another one and it signals the intention to interact amicably. Rank order affected the display of tail up posture: it was more frequently displayed by low-ranking cats, and high-ranking individuals received it more often than other members of the social group. Then, tail up seems to be a signal by means of which a cat shows the recognition of the higher social status of the individual to whom is directed. We confirmed the association between tail up and other affiliative behavioural patterns and the individual variability in displaying them. Considerations on the evolution of the tail up as a visual signal will be discussed.  相似文献   

15.
Body size often varies among conspecific neonates. As larger adults generally have higher fitness than smaller conspecifics, it is adaptive for smaller neonates to subsequently gain relatively more size increments during larval development (catch‐up growth). Although catch‐up growth has been suggested in insects, inappropriate methods have been used to examine the size dependence of growth increments. Therefore, it remains unclear to what extent catch‐up growth is common among insects. The present study examined the size dependence of growth increments among larvae of Trypoxylus dichotomus using reduced major axis regression of final to initial body masses. Catch‐up growth was found consistently for larval instars. Furthermore, simulations of the size increments revealed that not only sexual divergence of the mean size, but also catch‐up growth within sexes plays a role in the development of sexual divergence in the body size distribution of T. dichotomus. The significance of catch‐up growth in body size evolution was discussed.  相似文献   

16.
Intravenously injected immune complexes (ICx) composed of bovine serum albumin (BSA) and rabbit anti-BSA were taken up by the liver. Insoluble complexes, made in antibody excess, were rapidly taken up by Kupffer cells and were metabolized within 24 h. Soluble complexes, made in antigen excess, were only partly taken up by Kupffer cells. In addition these complexes were bound, taken up and metabolized by endothelial cells. Until 2 h after injection soluble complexes could also be observed along the microvilli of hepatocytes. No signs of endocytosis in hepatocytes could be observed. It is concluded, that ICx can be taken up by Kupffer cells as well as by endothelial cells. The physical state of the complexes, soluble or insoluble, determines the cell type in which uptake occurs.  相似文献   

17.
The mast cell population is heterogeneous concerning its amine precursor and amine uptake. The immature cells incorporate amine precursors, but in more advanced stages of their maturation they take up only 5-HTP. The mature cells do not take up precursors only 5-HT. The thyroid gland and heart muscle mast cells take up the highest amount of 5-HT; this may be related with some specific function of the mast cells in these two organs. Neither of the mast cells would take up histamine, the compound is synthetised by the cells.  相似文献   

18.
To investigate the effects of bacteria (Burkholderia cepacia) on metal uptake by the hyperaccumulating plant, Sedum alfredii, a hydroponic experiment with different concentrations of Cd and Zn was conducted. It was found that inoculation of bacteria on S. alfredii significantly enhanced plant growth (up to 110% with Zn treatment), P (up to 56.1% with Cd treatment), and metal uptake (up to 243% and 96.3% with Cd and Zn treatment, respectively) in shoots, tolerance index (up to 134% with Zn added treatment), and better translocation of metals (up to 296% and 135% with Cd and Zn treatment, respectively) from root to shoot. In the ampicillin added treatment with metal addition, stimulation of organic acid production (up to an increase of 133% of tartaric acid with Cd treatment) by roots of S. alfredii was observed. The secretion of organic acids appears to be a functional metal resistance mechanism that chelates the metal ions extracellularly, reducing their uptake and subsequent impacts on root physiological processes.  相似文献   

19.
The induction of chromosome aberrations, micronuclei and SCEs was studied in hepatocytes of F344 rats exposed in vivo to hepatocarcinogens. Hepatocytes were isolated and allowed to proliferate in Williams' medium E supplemented with epidermal growth factor. Cells were fixed after a culture period of 48 h. Oral administration of dimethylnitrosamine at doses of 2.5-20 mg/kg body weight (bw) induced (1) chromosome aberrations in up to 27% of the metaphase cells 2-48 h after its administration, (2) SCEs with a frequency of up to 0.9 per chromosome 2-48 h after its administration, and (3) micronuclei in up to 2.9% of the cells 16-48 h after its administration. Oral administration of 2-acetylaminofluorene at doses of 6.25-200 mg/kg bw induced (1) chromosome aberrations in up to 35% of the metaphase cells after 2-48 h, (2) SCEs at up to 0.9 per chromosome and (3) micronuclei in up to 2.5% of the cells with a maximum after 4 h. Oral administration of CCl4, a non-genotoxic hepatocarcinogen, at a dose of 1600 mg/kg bw did not induce chromosome aberrations, SCEs or micronuclei within 4-72 h. Intraperitoneal injections of Trp-P-1, Glu-P-1, MeIQx, IQ and nitro-IQ resulted in chromosome aberrations in up to 16% of the metaphase cells and SCEs at up to 0.9 per chromosome, while injections of Trp-P-2 and Glu-P-2 produced SCEs at up to 0.7 and 1.1 per chromosome, respectively. The present method of in vivo cytogenetic assay using rats without partial hepatectomy or mitogen treatment in vivo should be useful for evaluating the tumor-initiating activities of hepatocarcinogens.  相似文献   

20.
Fusarium poae (Peck) Wollenw. occurred In maize ears with “pink rot” during 1985–1993 up to 18% of Fusarium isolates, with maximum frequency in 1990. Nivalenol and fusarenone X were produced under laboratory conditions by 13 out of 14 isolates up to 115 μg/g and 13.3 μg/g respectively. The same isolates produced diacetoxyscirpenol (DAS) up to 21.7 μg/g and 15-monoacetoxyscirpenol (MAS) up to 12.3 μg/g. However, In none of the strain cultures were T-2 toxin and HT-2 toxin detected. In samples of naturally Infected maize grain nivalenol was detected at levels of 1.8–32.5 μg/g and fusarenone X was not present. In corresponding axial stems were present both nivalenol (up to 13.5 μg/g) and fusarenone X (up to 2.4 μg/g).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号